1. Field of the Invention
The present invention relates to improvements in therapeutic material delivery device (vehicle) for delivering (implanting) a therapeutic material such as a coiled or capsulated radioactive source to an organism for radiotherapy, for example, of a patient suffering prostate cancer.
2. Description of the Related Art
Radiotherapy (brachytherapy) refers to a treatment made by allowing a radioactive beam to radiate to a morbid tissue suffering a prostate cancer, an esophagus cancer, or the like. Radiotherapy includes high-dose, external beam radiation treatment and low-dose close-distance radiation treatment.
It is present practice to employ the latter method as a method for improving a therapeutical effect depending upon a therapeutic site and reducing side effects. In this case, there is practiced a method in which a radioactive source having radioactivity in the form of a sealed radioactive source is implanted (caused to remain) in a diseased part or a part near a morbid part with a delivery needle for the radioactive source, to treat the diseased part. The present invention is applied to the above method using the sealed radioactive source. The radioactive source for use in the present invention is selected from those containing radioactive isotopes that are clinically utilizable, and examples thereof include isotopes of cobalt, phosphorus, strontium, cesium, palladium, yttrium, iridium, rhenium, etc. Particularly preferred are isotopes that radiate β rays.
The above delivery needle is constituted of an inner needle member having a tubular needle and an outer needle member having a sticking needle formed to have a sharpened forward end, and a plurality of the capsular radioactive sources having radioactivity and having a size of approximately 5 mm are charged into the above outer needle member with tweezers. The above radioactive sources are spaced with spacers formed of a biodegradable substance, and a wax is applied to the forward end of the above sticking needle, so that the above radioactive sources do not come off the sticking needle.
When capsular radioactive sources are implanted in a diseased part with a delivery needle having the above sticking needle, approximately five radioactive sources are charged into one sticking needle as described above and are linearly implanted in the diseased part. In this manner, approximately 25 sticking needles above (corresponding to 125 radioactive sources) are embedded in different implantation positions. In the implantation, the implantation positions are secured while monitoring the positions with an ultrasonic diagnosis apparatus, so that the diseased part is uniformly irradiated with the radioactive sources.
Coiled radioactive sources formed by coiling rod-like or wire-like radioactive sources are recently used in place of capsular radioactive sources. That is because the coiled radioactive sources have a large surface area each and the length of the radioactive sources per piece can be increased as compared with the capsular radioactive sources, so that the number of the radioactive sources required can be decreased. The coiled radioactive sources are therefore less frequently charged into the outer needle member as compared with the capsular radioactive sources. Further, there is the merit of being free from spots that are not irradiated with a radioactive ray (cold spots), since it is not required to insert the spacers.
However, when a conventional inner needle member having a tubular needle and a conventional outer needle member having a sticking needle, which are used for implanting capsular radioactive sources, are used for implanting coiled radioactive sources in a diseased part, the coiled radioactive sources come to be curved, so that the irradiation with a uniform dose of radioactive ray can be no longer possible.
It is therefore required to prepare a medical sticking needle having a three-layered structure formed of an inner needle member through which coiled radioactive sources are to be passed or generally an inner needle member for holding a therapeutic material such as radioactive sources and extruding them forward, a middle needle member for fixing the radioactive sources and an outer needle member that is to be inserted into a diseased part or an intended portion, that is, a therapeutic material delivery device. The present invention relates to improvements in the above delivery device for delivering a therapeutic material such as radioactive sources.
Further, the delivery device may be a therapeutic material delivery device that is formed of an inner needle member for holding a therapeutic material such as radioactive sources and extruding them forward, a cartridge chargeable with the therapeutic material and an outer needle member that is to be inserted into a diseased part or an intended portion. The present invention also relates to improvements in such a delivery device using said cartridge.